U.S. patent application number 09/947202 was filed with the patent office on 2003-03-20 for navigation system for mobile communication devices.
This patent application is currently assigned to Zi Corporation. Invention is credited to Simpson, Todd G., Williams, Roland.
Application Number | 20030054830 09/947202 |
Document ID | / |
Family ID | 25485717 |
Filed Date | 2003-03-20 |
United States Patent
Application |
20030054830 |
Kind Code |
A1 |
Williams, Roland ; et
al. |
March 20, 2003 |
Navigation system for mobile communication devices
Abstract
A navigation assistance system provides navigational guidance to
a user of a mobile appliance equipped with a radio transceiver. The
user can specify a destination address either directly or
categorically and select from any choices to resolve ambiguity. The
user submits the selected destination to a fixed radio system such
as a cellular telephony system which estimates the user position,
determines the relative location of the destination and sends to
the user appliance data which allows the display of approximate
range and bearing to the destination. The mobile appliance can be
equipped with a compass which can be electronic and which allows a
user to be shown the direction of travel in order to reach the
destination.
Inventors: |
Williams, Roland; (Pleasant
Hill, CA) ; Simpson, Todd G.; (Calgary, CA) |
Correspondence
Address: |
LAW OFFICES OF JAMES D. IVEY
3025 TOTTERDELL STREET
OAKLAND
CA
94611-1742
US
|
Assignee: |
Zi Corporation
|
Family ID: |
25485717 |
Appl. No.: |
09/947202 |
Filed: |
September 4, 2001 |
Current U.S.
Class: |
455/456.1 ;
455/566 |
Current CPC
Class: |
H04M 2250/10 20130101;
G08G 1/096883 20130101; G08G 1/096866 20130101; G01C 21/20
20130101; H04M 1/72403 20210101; G08G 1/096861 20130101; H04W 64/00
20130101; G08G 1/005 20130101 |
Class at
Publication: |
455/456 ;
455/566 |
International
Class: |
H04Q 007/20 |
Claims
What is claimed is:
1. A method for providing navigational assistance to a user of a
mobile communications device, the method comprising: cooperating
with at least one fixed base station to determine a geographical
location of the mobile communications device; sending data
representing a destination; receiving navigation data relative to
the destination; and representing the navigation data to the
user.
2. The method of claim 1 wherein the navigation data includes a
bearing to the destination.
3. The method of claim 1 wherein the navigation data includes a
range to the destination.
4. The method of claim 1 wherein representing comprises: deriving
oriented navigation data according to an orientation of the mobile
communications device; and representing the oriented navigation
data to the user.
5. The method of claim 4 wherein the oriented navigation data
includes a relative bearing to the destination wherein the relative
bearing is relative to an orientation of the mobile communications
device.
6. The method of claim 5 wherein the relative bearing is relative
to a directional orientation of the mobile communications
device.
7. The method of claim 4 where deriving comprises: determining a
compass heading of the mobile communications device; and forming
the oriented navigation data from the navigation data according to
the compass heading.
8. A mobile communications device which provides navigational
assistance to a user, the device comprising: a user interface
module; a data communication module which is capable of sending
data to and receiving data from at least one fixed base station; a
navigation module which is operatively coupled to the user
interface module, and the data communication module and which, when
activated by the user: receives from the user interface module
destination data representing a destination; causes the data
communication module to communicate the destination data to the at
least one fixed base station; causes the data communication module
to cooperate with the at least one fixed base station to determine
a geographical location of the mobile communications device;
receives, from the data communication module, navigation data
relative to the destination; and causes the user interface module
to represent the navigation data to the user.
9. The mobile communications device of claim 8 wherein the
navigation data comprises a bearing to the destination.
10. The mobile communications device of claim 8 wherein the
navigation data comprises a range to the destination.
11. The mobile communications device of claim 8 further comprising:
an orientation measuring device which is operatively coupled to the
navigation module; wherein the navigation module, when activated by
the user, also derives oriented navigation data from the navigation
data according to an orientation determined by the orientation
measuring device; and further wherein the navigation module causes
the user interface module to represent the navigation data to the
user by causing the user interface module to represent the oriented
navigation data to the user.
12. The mobile communications device of claim 11 wherein the
orientation measuring device is a compass.
13. The mobile communications device of claim 11 wherein the
oriented navigation data includes a relative bearing to the
destination wherein the relative bearing is relative to an
orientation of the mobile communications device.
14. The mobile communications device of claim 11 wherein the
oriented navigation data includes a relative bearing to the
destination wherein the relative bearing is relative to a
directional orientation of the mobile communications device.
15. A method for providing navigation assistance to a user of a
mobile communications device, the method comprising: determining a
location of the mobile communications device; and sending
navigation data representing the location to the mobile
communications device.
16. The method of claim 15 further comprising: receiving data
representing a destination of the mobile communications device;
wherein the navigation data specifies a relationship between the
location and the destination.
17. The method of claim 16 wherein the navigation data includes a
bearing to the destination.
18. The method of claim 16 wherein the navigation data includes a
range to the destination.
19. A base station for communications through a mobile
communications device, the base station comprising: a
communications module which is capable of conducting communications
with the mobile communications device; a mobile device location
module which is operatively coupled to the communications module
and which is capable of determining a location of the mobile
communications device; and a mobile device navigation module which
is operatively coupled to the communications module and the mobile
device location module and which can assist navigation of the
mobile communications module by: causing the mobile device location
module to determine a current location of the mobile communications
device; and causing the communications module to send navigation
data representing the current location to the mobile communications
device.
20. The base station of claim 19 wherein the mobile device
navigation module can assist navigation of the mobile
communications device by also: receiving data, through the
communications module, which represents a destination; wherein the
navigation data represents a relationship between the current
location of the mobile communications device and the
destination.
21. The base station of claim 20 wherein the navigation data
includes a bearing to the destination.
22. The base station of claim 20 wherein the navigation data
includes a range to the destination.
Description
FIELD OF THE INVENTION
[0001] This invention relates to the field of electronic navigation
systems and mobile communications devices and, in particular, to
navigation systems within mobile communication devices.
BACKGROUND OF THE INVENTION
[0002] Navigation has existed as an art since the earliest days of
human exploration. Techniques, though primitive, relied upon
determination of position relative to visible landmarks and was
confined to land areas for most of history. Navigation beyond sight
of land was haphazard and until recent times barely practical until
the invention of accurate chronometers. This history is detailed in
David Sobel, Longitude, Econo-Clad Books; ISBN: 0613022203 (October
1999).
[0003] The discovery that a radio transmitter could be located
relatively precisely was a landmark in air navigation in that such
location allowed accurate courses to be flown. However, determining
the position of the radio transmitter required the operator of
transmitter location equipment--typically the pilot or navigator of
an aircraft--to be rather sophisticated and to perform substantial
work, involving calculation by the navigator to establish the
interception point of two radials from different known radio
stations. This method of triangulation is a well understood survey
technique and a device known as a Radio Magnetic Indicator (RMI)
displays the bearing from an aircraft or other vehicle to each of
two selected radio beacons. By utilizing a movable compass card
slaved to the heading of the vehicle, the operator could now
determine, with the aid of a map, the position of the vehicle and
its approximate direction of travel (heading) all from a single
instrument. The arrival of distance measuring equipment (DME),
which determined distance along a course by measuring the transit
time of radio pulses, finally reduced the navigator's task to a
relatively mechanical procedure. However, these devices were bulky,
relied on accurately positioned radiating beacons and no small
amount of map reading skill on the part of the user.
[0004] In recent years, Global Positioning Satellite (GPS) systems
have put navigational abilities which were unimaginable just a
couple decades ago into the hands of the average person at a very
reasonable cost. GPS devices have been made sufficiently small and
compact so as to fit on the wrist of a user much like a wrist
watch.
[0005] Portable GPS devices are particularly helpful and therefore
popular with people for whom navigation is very important. Such
people include pilots, boat operators, and hikers for example. Some
models of cars are currently being equipped with GPS navigation
systems. However, the popularity of GPS devices is currently
limited to people with special navigation needs or as part of a
larger product such as a car in which the expense of a GPS device
is dwarfed by, and can be included in, the expense of the larger
product.
[0006] One significant reason for the limited popularity of GPS
devices is that they require sophisticated, special-purpose
circuitry to track numerous satellites and to cooperate with those
numerous satellites to determine a relative position of a
particular GPS device. Such special-purpose circuitry represents a
generally affordable, yet significant cost.
[0007] A low-cost, easily portable alternative to currently
available GPS devices for positioning information and personal
navigation would bring personal electronic navigation to many more
people.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention, a mobile
communications device such as a cellular telephone receives
navigation data indicating a relative position of the mobile
communications device to an intended destination to provide
navigation assistance to the user of the mobile communications
device. The mobile communications device requests such navigation
data from a fixed base station in communication with the mobile
communications device. In response to such a request, the base
station determines the approximate geographical location of the
mobile communications device in a conventional manner without
reliance on external position awareness on the part of the mobile
device. In addition, a bearing and range to the intended
destination from the measured location of the mobile communications
device is determined. The navigation data received by the mobile
communications device can include the determined bearing and range.
The navigation data can also include such things as latitude and
longitude of the mobile communications device, map data, and
progressive navigation instructions for example.
[0009] Further in accordance with the present invention, the mobile
communications device includes a compass for enabling directional
instructions to the user. In particular, the compass of the mobile
communications device is used, in conjunction with the bearing to
the intended destination, to determine a relative bearing to the
intended destination. The relative bearing, thus determined, can be
displayed as an arrow in the general direction of the intended
destination relative to a directional orientation of the mobile
communications device. The sampling of the compass of the mobile
communications device can be performed sufficiently frequently to
provide real-time and interactive navigation assistance to the
user. For example, when the compass is sampled multiple times per
second, the user can turn in either direction while holding the
mobile communications device and the indicated relative bearing to
the intended destination updates sufficiently frequently to provide
useful guidance to the user while turning. Thus, the user is
provided with a convenient and intuitive interface for determining
the direction to the intended destination relative to the user's
surroundings.
[0010] It should be appreciated that the relative bearing is
determined relative to the orientation of the mobile communications
device and not derived by rate of change of position as is done by
GPS devices. Thus, while a GPS device does not accurately reflect
heading of the GPS device while rotating about a single fixed
location, a mobile communications device using an included compass
in accordance with the present invention does.
[0011] It should be further appreciated that the range to the
destination from the measured location of the mobile communications
device can also be displayed to the user. However, the range to the
destination as displayed to the user is generally not affected by
the compass of the mobile communications device.
[0012] To determine a bearing and range to the intended
destination, the location of the mobile communications device is
determined. The location of the mobile communications device can be
determined using, for example, the Cursor.TM. remote unit location
system of Cambridge Positioning Systems of Cambridge, England, or a
similar technology from Cel-Lok of Calgary, Alberta, Canada. Such
location technologies are commercial service offerings designed to
support the Federal Communications Commission's (FCC's) mandate
that the locations of mobile telephones placing emergency calls
shall be determined and that information regarding the location of
such a mobile telephone shall be available to the responding
emergency service.
[0013] Once the location of the mobile communications device is
determined, the intended destination is compared to the location of
the mobile communications device to determine the bearing and range
from the mobile communications device to the intended
destination.
[0014] As the user moves toward the destination, the location of
the mobile communications device changes. Accordingly, the bearing
and range to the intended destination is determined periodically.
The frequency of such bearing and range periodic determinations can
be less than the frequency of the relative bearing updates made by
reference to the compass of the mobile communications device since
the directional orientation of the mobile communications device
typically changes more rapidly than does the location of the mobile
communications device when held by a pedestrian user.
[0015] The frequency at which the location of the mobile
communications device, and thus the bearing and range to the
intended destination, is updated depends at least partly on the
accuracy with which the location of the mobile communications
device can be determined and the rate at which that location is
likely to change. In addition, frequency of location updates can
depend on the level of service desired by the user. In particular,
by allowing modification of the period at which updates are made,
the quality or grade of service offered can be adjusted to meet the
willingness of the user to pay for different grades of service.
During periods of heavy demand, decreasing the frequency of updates
frees processing and communications bandwidth to serve a larger
number of users of such a navigation service.
[0016] Thus, by making a relatively small change to mobile
communications devices, namely, incorporating the ability to
receive and display navigation data and including a small compass;
such devices can be made to provide navigational guidance
capability to users comparable to what is currently provided by
relatively expensive GPS guidance systems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a diagram showing a mobile communications device
and base station which cooperate to provide navigation guidance to
a user of the mobile communications device in accordance with the
present invention.
[0018] FIG. 2 is a block diagram showing elements of the mobile
communications device and base station of FIG. 1 in greater
detail.
[0019] FIG. 3 is a logic flow diagram showing the navigation
process of the mobile communications device in accordance with the
present invention.
[0020] FIG. 4 is a logic flow diagram showing the navigation
process of the base station in accordance with the present
invention.
[0021] FIG. 5 is a display view showing an illustrative navigation
display in accordance with the present invention.
[0022] FIG. 6 illustrates determination of bearing and range from
the mobile communications device to the destination using Cartesian
coordinates.
[0023] FIG. 7 illustrates determination of bearing and range from
the mobile communications device to the destination using radial
coordinates.
[0024] FIGS. 8 and 9 are display views of respective alternative
embodiments.
DETAILED DESCRIPTION
[0025] In accordance with the present invention, the location of a
mobile communications device 102 (FIG. 1), which can be a cellular
telephone for example, is determined by one or more base stations
106 and information about the determined location is communicated
to mobile communications device 102 for representation to the user.
In particular, the location is represented in this illustrative
embodiment as a relative bearing and range to a destination. It
should be appreciated that the destination can be a fixed location
which is specified by an address or other location specification
such as latitude/longitude coordinates or a mobile target such as
other mobile communications devices.
[0026] FIG. 1 shows mobile communications device 102 which is in
communication with a base station 106 through a fixed-location
antenna 104. In the illustrative embodiment described herein,
mobile communications device 102 is a cellular telephone. However,
it is appreciated that mobile communications device 102 can be any
of a number of other types of mobile communications devices
including, without limitation, a two-way pager, a personal digital
assistant (PDA) with communications capability, or a mobile modem
such as the Ricochet.TM. mobile modem available from Metricom, Inc.
of San Jose, Calif.--including or excluding an attached personal
computer.
[0027] Mobile communications device 102 and base station 106,
particularly elements which cooperate to assist navigation, are
shown in greater detail in FIG. 2. Mobile communications device 102
includes communication logic 202 which cooperates with
communication logic 212 of base station 106 to carry out voice
communications in a conventional manner. In this illustrative
embodiment, communication logic 202 and communication logic 212
cooperate to carry out mobile telephone communications in a manner
which is conventional for cellular telephones and base stations.
Such mobile telephone communications includes, for example, (i)
channel changing or frequency hopping for spread-spectrum
protocols, (ii) hand-offs to other base stations as mobile
communications device 102 moves from the region of one base station
to the region of another, (iii) control of transmit power of mobile
communications device 102, (iv) full-duplex voice communication or
common variants, and (iv) digital data communication according to
any of a number of data communication protocols. Such data
communication protocols include, for example, circuit-switched data
services for Global System for Mobile Communications (GSM)
networks, circuit-switched data service for CDMA networks, and
Cellular Digital Packet Data (CDPD). Data messages exchanged
between mobile communications device 102 and base station 106 as
described below are exchanged according to such a data
communications protocol. It should be appreciated and understood
that any packet data structure and transmission protocol consistent
with mobility can used to exchange such data messages between
mobile communications device 102 and base station 106 including,
without limitation, emerging standards for Wireless Area Networks
such as IEEE 802.11x (currently IEEE 802.11b) and the Bluetooth
defacto standard.
[0028] Mobile communications device 102 also includes user
interface and input/output (I/O) logic 208. Mobile communications
device 102 include a keypad 110 (FIG. 1), a display 112, and a
speaker and microphone for normal voice communication. While a
typical telephone-style keypad 110 is shown, it should be
appreciated that generally any type of user input device can be
used. For example, such user input devices include, without
limitation, keypads with button layouts other than that shown in
FIG. 1, touch-sensitive screens with either virtual keypads or
hand-writing recognition, speech recognition circuitry and logic,
and graphical user interface input devices. User interface and I/O
logic 208 generates signals in response to physical manipulation of
keypad 110 (FIG. 1) by the user and displays textual and/or
graphical information to the user in display 112 and can also
present auditory information through a speaker or headset jack to
the user as well. User interface and I/O logic 208 (FIG. 2) and
communication logic 202 combine to provide communications through
mobile communications device 102 in a conventional manner.
[0029] Mobile communications device 102 further includes navigation
logic 204 which assists the user in navigating from a current,
unknown location to a desired destination. The user initiates
navigation processing by navigation logic 204 by pressing, for
example, a dedicated button of keypad 110 (FIG. 1) or by traversing
a user-interface menu using conventional user-interface techniques.
Processing by navigation logic 204 in response is illustrated in
logic flow diagram 300 (FIG. 3).
[0030] In step 302, navigation logic 204 initiates a navigation
mode in response to the user's issued navigation command.
[0031] In step 304, navigation logic 204 receives data from the
user specifying a destination to which the user would like to
travel. The user can enter the destination in any of a number of
ways. The user can enter numerical values representing latitudinal
and longitudinal coordinates of the destination or generally any
alphanumeric sequence identifying a destination or waypoint using
keypad 110. The user can enter a street address using keypad 110
using a multi-tap technique for entering letters or using a
predictive technique such as the predictive text entering technique
known as the eZiText.TM. text entry system by Zi Corporation of
Calgary, Alberta, Canada. Descriptions and demonstrations of the
eZiText.TM. text entry system can be found at Zi Corporation's web
site (http://www.zicorp.com). Briefly, a number of characters are
mapped to each key of a limited keypad and key presses are
disambiguated using predictive analysis. As a simple example, the
typical telephone keypad associates the "2" key with the letters,
"a," "b," and "c." A single press of the "2" key can be interpreted
as an "a," a "b," or a "c." Pressing the "2" key twice can be the
beginning of any of a number of words. For example, "cat," "bat,"
and "act" all begin with the "2-2" sequence. All such words are
sorted according to predicted usage frequency and the user can
select a predicted word at any time, thus reducing significantly
the number of key presses required to specify various words.
[0032] Of course, it should be appreciated that entered text is not
limited to the Latin/Roman alphabet. Ideographic languages, such as
Chinese, can also be recognized as described in U.S. Pat. No.
5,109,352 to Robert O'Dell which is incorporated herein by
reference.
[0033] If mobile communications device 102 has access to the World
Wide Web and includes a browser (e.g., if mobile communications
device 102 is a WAP-enabled cellular phone or a PDA with World Wide
Web browsing capability), the destination address can be imported
from a web-page viewed by the user. In addition, the user can cause
selected addresses to be stored in a "favorites" list from which
the user can select such a previously entered address in step 304.
Furthermore, if the destination is a mobile target such as another
mobile communications device, the destination can be specified by a
code number such as a telephone number of the mobile target.
[0034] Logic which is used by the user to enter data identifying
the destination can reside in navigation logic 204 or in navigation
server logic 216 which cooperates with navigation logic 204 to
provide the navigation assistance described herein. Navigation
server logic 216 can, for example, assist in predictive
interpretation of keypad buttons pressed by the user. In
particular, navigation server logic 216 corresponds to a fixed base
station 106 and therefore can limit street names to those of
streets within a predetermined range of base station 106. In
addition, navigation server logic 216 can provide a list of cities
within a predetermined range of base station 106 such that the user
can select a city from this list such that using a rather limited
(in some embodiments) keypad 110 to enter an alphanumeric city name
is obviated. Furthermore, upon selection of a destination region
such as a city, navigation server logic 216 can retrieve a list of
predetermined locations and associated data corresponding to the
selected destination region.
[0035] After step 304 (FIG. 3), processing by navigation logic 204
(FIG. 2) transfers to loop step 306 which, in conjunction with next
step 322, defines a loop in which steps 308-320 are repeated until
the user terminates the navigation function using conventional
user-interface techniques such as pressing or pressing and holding
a dedicated button in keypad 110 for example.
[0036] In step 308, navigation logic 204 polls the location of
mobile communications device 102. In particular, navigation logic
204 requests that remote unit location logic 214 determines the
location of mobile communications device 102. In one embodiment,
polling location in step 308 includes sending data identifying the
destination entered by the user. In an alternative embodiment,
navigation logic 204 and navigation server logic 216 cooperate to
interpret user-generated signals representing the destination
intended by the user in step 304. Accordingly, navigation server
logic 216 knows the destination intended by the user, and no such
destination data is included in the location poll of step 308 in
this alternative embodiment.
[0037] In response to the location poll of step 308, navigation
server logic 216 acts as shown in logic flow diagram 400 (FIG. 4).
In step 402, navigation server logic 216 (FIG. 2) initiates
determination of a geographical location of mobile communications
device 102 through remote unit location logic 214. In this
illustrative embodiment, remote unit location logic 214 is the
Cursor.TM. remote unit location system of Cambridge Positioning
Systems of Cambridge, England. The Cursor.TM. remote unit location
system is known and is not described herein. Briefly, remote unit
location logic 214 uses base station 106 and other fixed stations
of known position which are in communication with base station 106
to determine an approximate physical location of mobile
communications device 102.
[0038] In step 404, navigation server logic 216 (FIG. 2) calculates
a magnetic bearing, i.e., a direction relative to magnetic North,
and a range, i.e., distance to the destination. The mathematics
involved in calculating bearing and distance from the location of
mobile communications device 102 to the destination is
straightforward and generally includes nothing more complex than
simple trigonometry. While such mathematics are generally known,
they are described briefly below for completeness. In step 406,
navigation server logic 216 sends the magnetic bearing and range to
mobile communications device 102.
[0039] In step 310 (FIG. 3), navigation logic 204 (FIG. 2) receives
the magnetic bearing and range to the destination from base station
106. In an alternative embodiment, navigation logic 204 receives
only location information pertaining to the location of mobile
communications device 102 (FIG. 1) and calculates the magnetic
bearing and range to the destination from the location of mobile
communications device 102. This alternative embodiment requires
additional processing resources within mobile communications device
102 to perform such calculations and requires determining of a
location of the destination. In particular, if the destination is
specified as a street address, mobile communications device 102
determines coordinates for the destination from the street address
in this alternative embodiment. Such can be accomplished by
receiving such destination coordinates from navigation server logic
216 (FIG. 2) in response to location polling in step 308 (FIG. 3)
or during destination entering in step 304 if navigation logic 204
(FIG. 2) and navigation server logic 216 cooperate during
destination entry in the manner described above. Alternatively,
mobile communications device 102 can include sufficient data and
logic to determine coordinates of the destination from an address
or other location information known by the user. If the destination
is mobile, e.g., another mobile communications device, remote unit
location logic 214 determines the location of the mobile
destination in generally the same manner that remote unit location
logic 214 determines the location of mobile communications device
102 in step 402 (FIG. 4)and communicates the location of the mobile
destination to navigation server logic 216 (FIG. 2).
[0040] Regardless, navigation logic 204 has a magnetic bearing and
a range to the destination by completion of step 310 (FIG. 3)
whether such bearing and range are determined by navigation logic
204 or navigation server logic 216. Loop step 312 and next step 320
define a loop in which steps 314-318 are performed for a
predetermined period of time. The predetermined period of time is
selected generally according to a number of factors which
collectively determine how frequently the location of mobile
communications device 102 (FIG. 1) should be updated. Such factors
can include, for example, the accuracy of determination of the
location of mobile communications determined by remote unit
location logic 214 (FIG. 2), the precision with which range
information is to be displayed to the user as described below, and
the speed with which the user and mobile communications device
could be moving. In one embodiment, the predetermined period of
time is fifteen (15) seconds. In fifteen (15) seconds, a user of
mobile communications device 102 can walk about seventy-five (75)
feet which close approximates the accuracy of currently used
locations technology in a typical multi-path radio environment at 1
GHz. In an alternative embodiment, the predetermined period of time
is approximated by performing a predetermined number of iterations
of the loop of steps 312-320 (FIG. 3). In addition, the
predetermined period of time can be adjusted according to any of a
number of factors including, for example, a level of service
requested by the user, the speed with which the user (and thus
mobile communications device 102) is moving, and the availability
of processing and/or communications bandwidth of base station 106.
The speed with which mobile communications device 102 is moving can
be determined by compared determined locations of mobile
communications device 102 at various times and calculating the
rates at which the location of mobile communications device 102
changes.
[0041] In step 314, navigation logic 204 (FIG. 2) retrieves data
representing a compass heading from a electronic compass 206
included within mobile communications device 102. In this
illustrative embodiment, electronic compass 206 is the Vector 2X
compass module available from Precision Navigation, Inc. of Santa
Rosa, Calif. Generally, electronic compass 206 can be any type of
compass which can be integrated with mobile communications device
102. Examples include magnetoresistive compasses such as those
described in Application Note AN00022 by Philips Semiconductor of
Eindhoven, the Netherlands entitled "Electronic Compass Design
Using KMZ51 and KMZ52" and compasses using the Hall effect for
orientation determination.
[0042] In step 316 (FIG. 3), navigation logic 204 (FIG. 2)
calculates a relative bearing using the magnetic bearing received
in step 310 (FIG. 3) and the compass heading received in step 314.
In general, the relative bearing is the difference between the
magnetic bearing and the compass heading. In particular, the
relative bearing is the magnetic bearing less the compass heading
and adjusted by an integer multiple of 360 degrees such that the
relative bearing is between 0 and 359 degrees. In step 318 (FIG.
3), navigation logic 204 (FIG. 2) displays the relative bearing and
range to the destination in display 112 as shown in FIG. 5.
[0043] In step 318 (FIG. 3), navigation logic 204 (FIG. 2) displays
a pointer 502 (FIG. 5) in display 112. Pointer 502 is shown in the
direction of the relative bearing to the destination calculated in
step 314 (FIG. 3). Thus, pointer 502 (FIG. 5) points directly to
the physical location of the destination entered by the user and
therefore assists the user in traveling to the destination. Other
useful navigation information is included in display 112 in step
318 (FIG. 3). For example, the range to the destination is
displayed as text 504 (FIG. 5). The relative bearing is represented
numerically in text 506. The magnetic bearing is represented
numerically in text 508. The compass heading of mobile
communications device 102 is represented numerically in text 510
and graphically by compass rose 514. In addition, the destination
entered by the user is represented by text 512.
[0044] Of course, other types of informational displays can be used
to aid navigation by the user according to the location and compass
heading of mobile communications device 102. For example, a moving
map can be displayed in display 112. Alternatively, progressive
navigation instructions (such as "turn left at the intersection
ahead of you--Kearny Ave.") can be displayed to the user in display
112. In addition, the current position of mobile communications
device 102 can be represented in latitude and longitude.
[0045] After step 318 (FIG. 3), processing transfers through next
step 320 to loop step 312 in which steps 314-318 are repeated until
the predetermined period of time has expired. Thus, a new compass
heading is retrieved in step 314, a new relative bearing is
calculated in step 316, and the new relative bearing is displayed
in step 318. Thus, for the predetermined period of time, the
display shown in FIG. 5 is continually updated in real time as the
user turns toward pointer 502 to move toward the destination. The
real-time reaction of pointer 502 to movement by the user assists
the user tremendously in becoming oriented toward the destination.
Of course, the range will not change, nor will the magnetic
bearing, until an updated location of mobile communications device
102 (FIG. 1) is polled.
[0046] After the predetermined period of time has expired,
processing transfers from loop step 312 (FIG. 3) through next step
322 to loop step 306 and steps 308-320 are repeated. Thus, a new
location of mobile communications device 102 (FIG. 1) is determined
in steps 308-310 (FIG. 3), and the navigation display of FIG. 5 is
continually updated in the manner described above in steps 312-320
(FIG. 3). Since the new location of mobile communications device
102 (FIG. 1) is determined, the range as represented by text 504
(FIG. 5) and the magnetic bearing as represented by text 508 can
change to show the user progress toward the destination.
[0047] Thus, mobile communications device 102 (FIG. 1) can provide
navigation assistance similar to that provided by GPS systems at
nominal additional cost. Although mobile communications device 102
is described above to include compass 206 (FIG. 2) and to use
compass 206 to provide directional navigation assistance as
described in conjunction with steps 312-320 (FIG. 3), significant
navigation assistance can be provided without compass 206 (FIG.
2).
[0048] Without compass 206, steps 312-320 (FIG. 3) are replaced
with a single display navigation step in which navigation data
received from navigation server logic 216 (FIG. 2) is displayed to
the user on display 112 (FIG. 1). Such navigation data can be as
simple as a general direction such as North by Northwest (or "NNW")
displayed on display 112. Simple directional guidance as this can
be very helpful to a user who (i) has a magnetic compass, (ii) has
general directional awareness, or (iii) can deduce direction from
her environment. For example, a user can identify North by noticing
a direction of an increasing trend in numerical street addresses
along a "North" street such as North First Street. Adding a range
to the destination to display 112 improves navigational assistance
provided by mobile communications device 102.
[0049] Navigation assistance provided by mobile communications
device 102 without compass 206 (FIG. 2) can be even more
sophisticated. For example, a vector from a previous position
determined by remote unit location logic 214 to a current position
can be used to estimate a directional orientation of mobile
communications device 102. Other displays can provide quite helpful
navigation data to the user without reliance upon directional
orientation of mobile communications device 102 as shown in FIGS. 8
and 9.
[0050] FIG. 8 shows a display in which an icon 802 representing the
current position of mobile communications device 102 as determined
by remote unit location logic 214 (FIG. 2) superimposed over a map
of the surrounding area. The display also includes an icon 804
(FIG. 8) representing the intended destination as specified by the
user in the map of the display. As the user continues to move in an
attempt to reach the destination, the position of icon 802 in the
map of the display is updated. By noting changes in the position of
icon 802 in relation to the position of icon 804, the user can very
effectively navigate to the destination.
[0051] FIG. 9 shows a display in which an icon 902 represents the
current position of mobile communications device 102 as determined
by remote unit location logic 214 (FIG. 2). An icon 904 represents
the intended destination. As the user, and therefore mobile
communications device 102, moves in an attempt to reach the
destination represented by icon 904, a path 906 is shown and
updated in display 112. Path 906 is simple and yet is effective in
representing to the user progress toward the destination and a
relative direction (i.e., right or left) to which the user should
continue in order to reach the destination.
[0052] Thus, even without compass 206 (FIG. 2), mobile
communications device 102 and base station 106 cooperate to provide
exception navigational guidance to a user at nominal additional
cost.
[0053] As described above, simple mathematics are used to calculate
a relative bearing and range to the destination from the determined
location of mobile communications device 102. FIG. 6 illustrates
such calculation involving two-dimensional linear coordinates. FIG.
7 illustrates such calculation involving radial coordinates. Of
course, it should be appreciated that determination of a direction
and distance from mobile communications device 102 to the
destination can be accomplished using a variety of known and
conventional mathematical methods.
[0054] In both instances, the location of mobile communications
device 102 as determined by remote unit location logic 214 (FIG. 2)
is expressed in radial coordinates. In particular, in this
illustrative embodiment, the location of mobile communications
device 102 is expressed as (.theta..sub.m, .rho..sub.m) where
.theta..sub.m is the radial on which mobile communications device
102 is located relative to base station 106 expressed in degrees
from magnetic north and .rho..sub.m is the distance of mobile
communications device 102 from base station 106. Similarly, the
location of destination is expressed herein as (.theta..sub.d,
.rho..sub.d) where .theta..sub.d is the radial on which the
destination is located relative to base station 106 expressed in
degrees from magnetic north and .rho..sub.d is the distance of the
destination from base station 106. The desired information is
expressed herein as (.theta., .rho.) where .theta. is the magnetic
bearing from mobile communications device 102 to the destination
expressed in degrees from magnetic North and .rho. is the distance
from mobile communications device 102 to the destination. While
degrees are described herein as the units in which angles are
expressed, it is appreciated and any unit of angular measurement
can also be used. Measuring angles in degrees from magnetic North
makes calculation of relative bearing for display to the user
particularly straightforward.
[0055] In the embodiment illustrated by FIG. 6, radial coordinates
of mobile communications device 102 and the destination are
converted to two-dimensional linear coordinates, namely, (x.sub.m,
y.sub.m) for the location of mobile communications device 102 and
(y.sub.d, x.sub.d) for the location of the destination. The
following equations are used to perform such a conversion:
x.sub.m=.rho. sin .theta.
y.sub.m=.rho. cos .theta.
[0056] Similar equations are used to convert the location of the
destination to two-dimensional linear coordinates. The
straight-line path from mobile communications device 102 to the
destination is calculated as follows:
dx=x.sub.d-x.sub.m
dy=y.sub.d-y.sub.m
[0057] To present the user with a direction and distance, the
relative bearing and range are calculated as follows:
.rho.={square root}{square root over (dx.sup.2+dy.sup.2)}
[0058] 1 = arc tan ( y x )
[0059] The approach illustrated in FIG. 6 has the advantage of
working with few exceptions. One exception is when dx is zero.
Simple logic resolves that problem, namely, the magnetic bearing is
360-degrees (magnetic North) if dy is positive and is 180-degrees
(magnetic South) otherwise when dx is zero.
[0060] Since the precision of the magnetic bearing determined by
navigation server logic 216 (FIG. 2) is effectively limited by the
resolution of display 112 (FIG. 1) and by the relatively simple
needs of a pedestrian navigating through a city, lookup tables can
be used to significantly simplify the computation of trigonometric
functions identified above. Generally, relative bearing accuracy
within about plus or minus five (5) to ten (10) degrees is
sufficient for pedestrian navigation.
[0061] Of course, the magnetic bearing and range can be determined
using other coordinate systems such as a radial coordinate system
as shown in FIG. 7. Distances A and B are determined according to
the following equations:
A=.rho..sub.d cos[180-(.theta..sub.d-.theta..sub.m)]
B=.rho..sub.d sin[180-(.theta..sub.d-.theta..sub.m)]
[0062] To determine magnetic bearing and range, the angle is
determined according to the following equation: 2 = arc tan ( B m +
A )
[0063] The magnetic bearing and range are determined from .alpha.
as follows:
.theta.=(180-.theta..sub.m)-.alpha.
[0064] 3 = B sin
[0065] As described above, the above equations use angles which are
relative to magnetic North from base station 106. If base station
106 determines such angles relative to true North or some other
reference angle, the angles are converted to magnetic headings
using the magnetic deviation for the fixed location of base station
106.
[0066] The above description is illustrative only and is not
limiting. Instead, the present invention is defined solely by the
claims which follow and their full range of equivalents.
* * * * *
References